Recently, a semiconductor device having a plurality of semiconductor chips stacked thereon has been developed. Many of them have been intended for electrical connection where electrodes of the semiconductor chips are bonded with wires or leads. However, the provision of the wires has imposed limitations on downsizing.
Additionally, it has been developed that a thorough hole is formed in the semiconductor chip and molten solder is filled in the through hole for electrical connection. However, when the solder is filled in a narrow through hole, a void is generated and thus the reliability in electrical connection is hard to secure.